A RF device connector (hereinafter referred to as an RF connector or a connector) for communication equipment is an electromechanical element for connecting a conductor (for example, a wire) with an appropriate paired device, thereby enabling connection and disconnection of microwave signals. In existing communication products, a ½″ RF coaxial cable and coaxial RF connectors mounted at the two ends of the cable are generally adopted for RF signal transmission between a commonly used remote radio unit (RRU) and an antenna. In order to prevent water from permeating along the cable from the RF connector (which may affect safe and stable operation of the cable and the communication equipment), waterproof sealing treatment is performed on a portion of the RF connector connected to the communication equipment or the smart antenna.
Traditional waterproof sealing treatment mainly includes four techniques: namely, a waterproof cement adhesive tape winding, a waterproof heat-shrinkable sleeve, a waterproof cold-shrinkable sleeve and a waterproof box. The waterproof cement adhesive tape winding method is relatively widely used, but in equipment with compact space, this method can be extremely difficult and require extreme time and labor. As the cement in the center of the interface easily expands and overflows under heating, the service life is typically only 2-3 years and regular maintenance and replacement are required, and the subsequent maintenance cost and disconnection may be difficulty. Additionally, if a technician winds the cement adhesive tape incorrectly, it may lead to poor waterproofing. The heat-shrinkable sleeve requires a special heating tool and thus has certain limitations during outdoor construction. The cold-shrinkable sleeve and the waterproof box are relatively convenient, but relatively high in cost, and the waterproofing of the two methods may be unreliable; moreover, subsequent maintenance using these two methods may also be quite complex and time-consuming.
In a mobile communication system, passive intermodulation (PIM) is gradually becoming a major cause of interference. PIM refers to a passive intermodulation product produced when the RF signal power of two or more frequencies appear in a passive device simultaneously; such a passive intermodulation product is a mixed signal produced due to a nonlinear characteristic of connection of heterogeneous materials, wherein one representative mixed signal is called a third-order intermodulation signal. The passive intermodulation product may interfere with a receiver, and may lead to abnormal operation of the receiver in a severe case; hence, it can be crucial to suppress or eliminate PIM.
With the constant development of communication systems, increasingly high PIM performance is required of connectors and jumpers, in particular dynamic passive intermodulation performance. Existing coaxial connectors are mainly reinforced with welds and/or via injection molding. However, to mount connectors outdoors, an on-site technician needs to manually mount cables, and pre-assembled connectors are mostly used. As the cables are typically flexible coaxial cables, when the cables bend or twist significantly, the contact surfaces of the contact portions between the ends of the cables and the connectors may be separated and deformed to a certain extent, leading to degradation of PIM performance. In one proposed solution, the tail nuts of the connectors generally are lengthened to protect the ends of the cables and to stabilize connected sections; however, this method typically results in high-cost connectors.
U.S. Patent Publication No. US2014/0097022A1 describes a sealing element for interconnection of a cable and a connector, wherein the sealing element comprises an integrated elastic body and a main duct penetrating through the elastic body. The main duct is provided with a main cable outer diameter sealing portion at a cable end. The main cable outer diameter sealing portion is adjacent to a main connector cavity portion, which is adjacent to a coupling nut cavity portion, and the coupling nut cavity portion is adjacent to a connector necking sealing portion at a connector end. The coupling nut cavity portion is longitudinally aligned to a coupling nut of a connector and designed to have a greater inner diameter than the main cable outer diameter sealing portion and the connector necking sealing portion. It may be desirable to seek further solutions to improve PIM performance.